Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Biochemistry, Cellular, and Molecular Biology Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Cell Rep. 2019 Sep 17;28(12):3131-3143.e5. doi: 10.1016/j.celrep.2019.08.048.
The canonical cortical microcircuit has principally been defined by interlaminar excitatory connections among the six layers of the neocortex. However, excitatory neurons in layer 6 (L6), a layer whose functional organization is poorly understood, form relatively rare synaptic connections with other cortical excitatory neurons. Here, we show that the vast majority of parvalbumin inhibitory neurons in a sublamina within L6 send axons through the cortical layers toward the pia. These interlaminar inhibitory neurons receive local synaptic inputs from both major types of L6 excitatory neurons and receive stronger input from thalamocortical afferents than do neighboring pyramidal neurons. The distribution of these interlaminar interneurons and their synaptic connectivity further support a functional subdivision within the standard six layers of the cortex. Positioned to integrate local and long-distance inputs in this sublayer, these interneurons generate an inhibitory interlaminar output. These findings call for a revision to the canonical cortical microcircuit.
经典的皮质微电路主要由新皮质的六层之间的层间兴奋性连接定义。然而，功能组织尚未被充分了解的第 6 层（L6）中的兴奋性神经元与其他皮质兴奋性神经元形成相对较少的突触连接。在这里，我们发现 L6 内的一个亚层中的绝大多数 Parvalbumin 抑制性神经元通过皮质层向软脑膜发送轴突。这些层间抑制性神经元接收来自两种主要类型的 L6 兴奋性神经元的局部突触输入，并且比邻近的锥体神经元接收更强的来自丘脑皮质传入的输入。这些层间中间神经元的分布及其突触连接进一步支持了皮质的标准六层中的功能细分。这些中间神经元位于该亚层中，用于整合局部和远距离输入，从而产生抑制性的层间输出。这些发现要求对经典皮质微电路进行修订。
